Quantum gravity (QG) is the field of physics which attempts to develop scientific models that unify quantum mechanics (describing three of the four known fundamental interactions) with general relativity (describing the fourth, gravity).

In another type of experiment, photons can be trapped in a cavity and manipulated. They can be observed without being destroyed through interactions with atoms in cleverly designed experiments.

According to Quantum Mechanics:
An observer is anything that can cause a wave function to collapse.
The interpretation of wave function collapse (usually referred to as “the measurement problem”)
Now when photons can be trapped in a cavity and manipulated.
How they can be observed without being destroyed!?
through interactions with atoms in cleverly designed experiments!?